Various styles of rotatable cutting bits for use in mining and construction operations are well known. For example, one common style of rotatable cutting bit useful in mining and construction operations has a generally conical shape working head having secured to the apex of the head by brazing an axially disposed insert of cemented tungsten carbide. Depending from the conical shape working head is a shank which is inserted into a bore within a cutting bit block.
During mining and construction operations the cutting bit is generally utilized in a machine having a power driven cutter wheel. The power driven wheel is mounted on a horizontal shaft with the plane of the wheel disposed vertically. The wheel has on its periphery an array of cutting bits mounted in a plurality of permanent cutting bit blocks adapted to hold the carbide tipped cutting bits. The cutting bit blocks typically include a bore of a cylindrical shape having a substantially cylindrical opening. The cutting bits are mounted generally tangentially on the peripheral rim of the supporting wheel so that through the rotation of the wheel about its axis, the cutting bits may attack the material to be broken up by the horizontal reach of the cutting bits operating in a vertical plane.
Exemplary of a cutting bit block and a cutting bit for use on a construction machine is U.S. Pat. No. 4,201,421. U.S. Pat. No. 4,201,421 discloses a cutting bit including a spring sleeve of cylindrical form with a slot extending the full length of the spring sleeve along substantially all of the shank of the cutting bit. The cutting bit is inserted shank first into the bore of the cutting bit block such that the spring sleeve frictionally engages the inside wall of the bore keeping the cutting bit in a working position on the rim of the wheel. During operation of the construction machine the cutting bits impact against a material to be worked thereby breaking the material into small fragments. As the cutting bits repetitively impact against the material to be worked, some of the small material fragments may work between the cutting bits and corresponding cutting bit blocks thereby wedging the cutting bits into the bore of the cutting bit blocks and preventing free rotation of the cutting bits and subsequent removal of the cutting bits from the bit blocks as required. The effect of the small material fragments pressed between the bit blocks and the cutting bits is that the removal of the cutting bits from the bit blocks is difficult, if not impossible, thereby necessitating increased machine downtime and expense.
Previously, a removal tool having a wedge shaped tine was driven between the conical cutting head and the bit block to pry the bit from the block. However, because the loose fragments of material are packed so tightly around the conical cutting head and the bit block, insufficient clearance is provided between the cutting head and the bit block for the removal tool to enter between the conical cutting head and the block.
To alleviate the aforementioned problems, we have invented a conical flanged cutting bit having a working head and a supporting shank depending therefrom. Formed integral with the base of the working head is an undercut. The undercut allows for the free insertion of a cutting bit removal tool to assist in the removal of the cutting bit from the socket mount. In a preferred embodiment, the undercut comprises opposing triangular cutouts to provide a variable reaction surface upon insertion of the bit removal tool within the undercut between the cutting bit and the cutting bit block.
Accordingly, one aspect of the present invention is to provide a conical flanged cutting bit including an undercut at the base of the conical flange to receive a bit removal tool. Another aspect of the present invention is to provide a conical flanged cutting bit including an undercut at the base of the conical flange to receive a bit removal tool that is simple and economical to manufacture.